Apparatus and method for exerting and maintaining a force between two bone members

Abstract

A bone staple includes a body and a pair of angled arms oppositely threaded into opposite ends of the body. The body has at least one generally flat periphery striking surface and a corresponding relatively sharp outward protrusion at an opposite side of the body from the striking surface. According to the disclosed method, the bone staple is implanted by driving the staple partly into two bone members and then rotating the body to threadably adjust the positions of the arms and thereby exert a force between the bone members. The staple is next driven further by striking the striking surface until the protrusion embeds beneath a bone surface to prevent rotation of the body. A driver tool useful for implanting the staple has a clamping head which receives the staple body and rigidly clamps the angled arms.

I claim: 
     
       1. Bone staple apparatus for exerting and maintaining a force between two bone members, comprising: a body having opposite axially aligned ends threaded axially in opposite directions to one another, a substantially flat peripheral striking surface, and a relatively sharp outward protrusion disposed laterally across said body from said striking surface; and   a pair of angled arms each having a threaded end portion in axial threaded engagement with a respective one of said axial ends of said body and a free end portion extending substantially perpendicular to the axis of said body for implantation into a bone member.   
     
     
       2. Bone staple apparatus according to claim 1, wherein said striking surface is planar. 
     
     
       3. Bone staple apparatus according to claim 1, wherein said protrusion defines a peripheral edge portion extending axially of said body. 
     
     
       4. Bone staple apparatus according to claim 1, wherein said arms are substantially right angular. 
     
     
       5. Bone staple apparatus according to claim 1, wherein said free end portion is serrated and has a sharpened tip. 
     
     
       6. Bone staple apparatus according to claim 5, wherein said free end portion has a serrated inner side and a smooth outer side. 
     
     
       7. Bone staple apparatus according to claim 1, wherein said body has a plurality of said striking surfaces facing outward of said body in different directions and a plurality of said protrusions, there being one of said protrusions disposed laterally across said body from each of said striking surfaces. 
     
     
       8. Bone staple apparatus according to claim 7, wherein said plurality of striking surfaces includes three striking surfaces defined by respective sides of a portion of said body which is substantially triangular in cross section. 
     
     
       9. Bone staple apparatus according to claim 8, wherein said portion of said body is enlarged and disposed intermediate said opposite ends of said body. 
     
     
       10. Bone staple apparatus according to claim 8, wherein said one protrusion is formed by a junction region of two of said three striking surfaces. 
     
     
       11. Bone staple apparatus according to claim 10, wherein said three striking surfaces are planar, forming sharp edges at their junctions. 
     
     
       12. Bone staple apparatus according to claim 8, in combination with a wrench having a head configured to receive said portion of said body and to engage said striking surfaces for rotating said body. 
     
     
       13. A method of exerting and maintaining a force between two bone members, comprising providing a bone staple including a body having laterally outward protrusion means and axially aligned opposite ends, said ends being threaded axially in opposite directions to one another, and a pair of angled arms each having a threaded end portion in axial threaded engagement with a respective one of said ends of said body and a free end portion extending substantially perpendicular to the axis of said body,   partially inserting the free end portions of said arms into said two bone members, respectively,   rotating said body to threadably adjust the relative positions of said arms axially of said ends of said body, and   further inserting said free end portions within said bone members and embedding said protrusion means beneath a bone surface to prevent further rotation of said body.   
     
     
       14. The method of claim 13, wherein the step of rotating includes turning said body in such a direction as to draw said arms together and compress said bone members against each other. 
     
     
       15. The method of claim 13, wherein the step of rotating includes applying a wrench to a triangular peripheral section of said body and turning said body with said wrench and wherein the step of embedding includes embedding a junction region of two sides of said triangular peripheral section beneath said bone surface. 
     
     
       16. The method of claim 13, wherein the step of further inserting includes subjecting said striking surface to an impact force.